The present invention relates generally to improved methods and systems for reducing noise and vibration characteristics in an automotive vehicle. More particularly, the invention relates to an anti-vibration damping material or pellet application system integrated along portions of automotive closure panels, such as portions of an automotive door frame or other panel assembly used to facilitate passenger or cargo ingress/egress to the vehicle. The present invention is applied to selected portions of an automotive vehicle through extrusion techniques resulting in the reduction of vibration and the improvement of sound absorption characteristics of the automotive vehicle.
Traditional automotive panel assembly operations generally require a specific pre-assembly manufacturing step or process, which occurs prior to final assembly of the vehicle. Typically for automotive door assemblies, this step or process involves the application of chemical compositions to a traditional door intrusion beam after the beam is shipped to the vehicle manufacturer from the intrusion device supplier. This process requires the vehicle manufacturer to allocate tooling and manufacturing facilities for the intrusion device application at either a separate stamping facility where the door is assembled or in the final vehicle assembly plant. One such technique employs the use of pumpable products applied to the intrusion device in the form of xe2x80x9cwetxe2x80x9d compositions, which can remain tacky or may otherwise be applied to the beam in a non-uniform manner. For instance, one popular technique utilizes a pumpable product consisting of a thermally activated polymeric material, which upon heat activation expands and fills the space defined between the intrusion device and the outer door panel.
While these prior art system perform well and are advantageous in many circumstances, they often require a large capital investment to integrate the pumpable product into the chosen manufacturing facility, utilize a large amount of floor space and maintenance clean-up resources at the stamping facility or vehicle assembly plant, and require an additional manufacturing process and labor demand. In turn, the manufacturer is required to devote both financial and technical resources to develop tooling for the pumpable product as well as transportation costs, which adds potential cost and delay, particularly if changes to the vehicle structure are implemented during the design stages.
Accordingly, there is need for a simple low cost system that provides an integrated anti-vibration damping material, in the form of a xe2x80x9cdryxe2x80x9d chemical product which can be extruded-in-place within targeted portions of an automotive panel assembly to reduce vibration characteristics and which can be employed across a wide range of different sizes or shapes of cavities found in automotive vehicles.
The present invention is directed to a vibration reduction system, and particularly one for automotive frame assemblies, such as (without limitation) vehicle door frame assemblies having a door intrusion device as well as any other automotive closure panel assemblies used in sliding doors, lift gates, or other designs used to facilitate the ingress and egress of passengers and/or cargo to an automotive vehicle. The system generally employs extrusion techniques in the form of a mini-applicator technology for facilitating the application of a dry chemical, anti-vibration damping material onto the intrusion device and/or other selected portion of the door frame, such as the beltline reinforcement, through an extrude-in-place process. It is contemplated that the material disclosed in the present invention functions as an anti-vibration dampener when expanded and bonded to the door intrusion device and optionally the inner and outer body panels, when the intrusion device, such as a intrusion device (now attached to the vehicle in the assembly operation), is processed through paint operations and process cycles typically encountered in a vehicle assembly plant. In one embodiment, the material is heat expandable and at least partially fills the cavity by cross-linking the door intrusion device and the inner and outer door panel during the painting operation thereby reducing noise and vibration characteristics of the vehicle as well as producing a more quiet door assembly when the vehicle door is opened and closed. In another embodiment, the material is a melt-flow material, and upon the application of heat will spread over a surface.
The present invention further serves to eliminate cleanliness and maintenance issues typically encountered through the use of a pumpable product process or application of xe2x80x9cwetxe2x80x9d chemical technology in either a pre-assembly stamping facility or a vehicle assembly plant since the anti-vibration damping material can be extruded or mini-application bonded onto the door intrusion device prior to paint operation processing. Hence, the present invention can be utilized by either the door intrusion device manufacturer or the vehicle manufacturer and extruded onto the door intrusion device itself for use by the vehicle manufacturer in the final assembly operation.
In a particular preferred embodiment, the damping material or medium comprises a plurality of pellets or a bead that is extruded along and onto portions of the intrusion device in a solid (though pliable) form in accordance with the teachings of commonly owned U.S. Pat. No. 5,358,397 (xe2x80x9cApparatus For Extruding Flowable Materialsxe2x80x9d), hereby expressly incorporated by reference, such type of apparatus being referred to herein as a xe2x80x9cmin-applicator.xe2x80x9d A preferred mini-applicator is an extrude-in-place device suitable for extrusion with or without robotic assistance, and which may be portable or remain stationary in a predetermined location. The use of a mini-applicator advantageously allows extrusion of meltable plastic materials of various section sizes or shapes directly at production or assembly lines. The material or medium is at least partially coated with an active polymer having damping characteristics or other heat activated polymer, (e.g., a formable hot melt adhesive based polymer or an expandable structural foam, examples of which include olefinic polymers, vinyl polymers, polyamides, EVA""s, thermoplastic adhesives, thermoplastic rubber-containing polymers, epoxies, urethanes or the like). The pellet then expands and bonds to the intrusion device and the body panel when exposed to the e-coat process as well as other paint operation cycles encountered in a final vehicle assembly facility. In addition, it is contemplated that the present invention may utilize an application of expandable material directly to a structural member or trim component of an automotive vehicle in an automated or otherwise expedited manufacturing process which may involve heating through traditional methods as well as welding and radiation curable technology or cleaning the selected member or part prior to application to assist in adhesion of the expandable material.
In a particular non-limiting embodiment, a plurality of pellets comprised of the vibration damping material or medium are transformed from a solid or dry chemical state to a visco-elastic stage through the use of a suitable mini-applicator which processes the pellets at a temperature sufficient to transform the pellets into a visco-elastic material capable of flowing onto the external surface of a intrusion device in a desired consistency, thickness, and pattern.
The heat application and other shear functions from the mini-applicator allows the material to flow in a uniform shape and manner as it is extruded onto an external surface of the intrusion device, such as a door intrusion beam, where it bonds. Once applied to the external surface of the intrusion device by the mini-applicator and no longer exposed to the heat source emanating from the mini-applicator, the material returns to it solid or dry chemical state and thereby remains disposed in place along the selected portion of the intrusion device. The intrusion device is then mounted within an automotive door assembly or other panel assembly by the vehicle manufacture in accordance with manufacturing techniques that are well known in the art. As the assembly is prepared for final assembly of the vehicle, it is processed through e-coat or other heat-inducing paint operations which result in expansion and bonding of the material from the intrusion device to either or both of the outer panel or the inner panel of the selected automotive closure panel, such as a door frame assembly having an inner door panel and an outer door panel, where it cures and remains in place. It is contemplated that the material expands from the external surface of the intrusion device and cross-links to the substrates, which can comprise either of both of a door inner panel and the door outer panel, thereby serving to reduce the noise and vibration emanating from the door assembly. Although the preferred embodiment discloses the material essentially chemically cross-linking from the external surface of an intrusion device, such as a door intrusion beam, into contact with the door outer panel, it will be appreciated that various patterns and applications of the material along the intrusion device would allow the material to expand and chemically cross-link with either or both of the door inner panel and door outer panel as well as any other substrate that may be utilized or encountered in a door assembly or other application which would facilitate either passenger of cargo access to a vehicle.
In one embodiment the vibration reducing medium is extruded-in-place onto an intrusion device in a continuous or non-continuous extrusion adjacent to one or more inner walls defining a cavity within an automotive door assembly. The vibration reducing medium is activated to accomplish transformation (e.g., expansion or flow) of the active polymer or polymer within the cavity after the door assembly is mounted onto the vehicle and the vehicle is exposed to heat as it is processed through the e-coat and paint operation cycles of a final automotive assembly plant, which is well known in the art. The resulting structure includes a wall or expansive extrusion that is coated over at least a portion of its surface with the vibration reducing medium acting to reduce vibration during transport and during functional operation of the door assembly. It will be appreciated that a preferred vibration reduction medium would consist of a damping material comprising a number of chemical formulations including, but not limited to, metal (such as steel, aluminum, etc.), rubber (such as a butyl or isobutylene polymer, copolymer, or similar elastomer having good damping characteristics), and plastic polymer chemistry (ideally material that would remain rigid at temperatures generally encountered by an automotive body skin during operation of the vehicle, for example xe2x88x9240xc2x0 C. to 190xc2x0 C.